hive-expert

name	hive-expert
description	Become an expert in Hive, a deterministic Swift graph runtime. Use when designing, implementing, testing, or debugging HiveCore graphs: schemas, channels, reducers, HiveRuntime supersteps/events, joins/fan-out, interrupts/resume, checkpointing, replay, and deterministic observability.

Hive Expert

Overview

Design and ship deterministic, testable graph runtimes in Swift 6.2 using HiveCore. Hive is intentionally focused on graph execution: schemas, channels, reducers, routing, joins, checkpoints, interrupts/resume, replay, and event traces.

Working Style

1. Ask only for missing product behavior:
   • What state belongs in global channels versus task-local channels?
   • Does the workflow need checkpointing, interrupt/resume, or replay compatibility?
   • What events or run outputs must be stable for tests?
2. Propose a minimal typed architecture:
   • HiveSchema + channel specs + reducers/update policies.
   • HiveGraphBuilder nodes, edges, routers, joins, and spawn.
   • HiveRuntime wired with HiveEnvironment(context:clock:logger:checkpointStore:).
3. Write Swift Testing coverage first for graph compilation, runtime behavior, checkpoints, and determinism.
4. Keep the public surface core-only. Do not add DSL, agent, model, RAG, Conduit, or Wax adapter APIs back into this package.

Quick Start

Hive is a BSP-style runtime:

• Channels are typed state slots declared in a HiveSchema.
• Writes target channels; reducers merge multiple writes per superstep.
• Each superstep runs the current frontier of tasks, then commits writes and schedules the next frontier.
• Static edges, routers, spawn, and join edges determine what runs next.
• Interrupt/resume, checkpointing, and replay validation are core runtime capabilities.

Read first:

• references/mental-model.md
• references/public-api-map.md
• references/sharp-edges.md

Core Invariants

• Channel IDs are globally unique per schema.
• .taskLocal channels must be .checkpointed and require a codec path.
• .global channels require a codec when persistence == .checkpointed.
• Reducers, routers, graph descriptions, event encodings, schema versions, and graph versions must be deterministic.
• Non-core user observability belongs in customDebug events.

Common Recipes

Fan-Out + Join

Use spawn to create worker tasks and HiveGraphBuilder.addJoinEdge to gate an aggregate node until all parents reach the barrier. Read: references/recipes-fanout-join.md

Human Approval Gate

Return HiveNodeOutput(interrupt:) to pause deterministically, then call resume with a HiveResume payload. Read: references/recipes-interrupt-resume.md

Checkpointed Runs

Provide a core HiveCheckpointStore through HiveEnvironment and enable HiveRunOptions.checkpointPolicy. Read: references/recipes-checkpointing.md

Deterministic Event Traces

Use HiveRunOptions(deterministicStreamBuffering: true) for stable stream ordering in golden tests. Read: references/testing-and-determinism.md

Troubleshooting

• Compilation fails: check start nodes, duplicate node IDs, unknown edge/router/join endpoints, and reserved join characters.
• Runtime fails before step 0: check missing codecs, schema version mismatch, graph version mismatch, and checkpoint fingerprints.
• Step aborts with no commit: check unknown channel writes, update policy violations, reducer errors, and checkpoint save errors.
• Event tests drift: check nondeterministic metadata, stream buffering options, and event buffer capacity.

Resources

scripts/

• scripts/hive_api_map.py: scan a Hive source checkout to list core public entry points.

references/

• references/mental-model.md: channel/reducer/superstep/join/interrupt/checkpoint mental model.
• references/public-api-map.md: current import and core API surface.
• references/sharp-edges.md: invariants, pitfalls, and gotchas.
• references/runtime-semantics.md: superstep commit rules, retries/cancellation, external writes, and event behavior.
• references/recipes-*.md: core graph runtime patterns.
• references/testing-and-determinism.md: golden tests and deterministic event semantics.
• references/troubleshooting.md: symptom to likely cause to fix.